The present invention relates to the field of paper drilling and more particularly relates to the manufacture of a drill bit for use in drilling through paper or other similar materials.
Paper drilling machines can be used to drill holes in paper or other materials. In a paper drilling machine, the holes are drilled by a series of drill bits. The drill bits are positioned generally vertically and located above a horizontal surface on which the materials to be drilled are placed. After the material to be drilled has been placed on the paper drilling machine, the drill bits are rotated at high speed and lowered to engage the material and drill through it. Once the drill bits have completed drilling the holes, the drill bits are raised so as to permit the drilled material to be removed, and the drilled material is removed.
There is a need for a paper drill bit with improved wear characteristics.
It is an object of the invention to provide a drill bit which overcomes or mitigates at least one of the disadvantages of the prior art.
In a first aspect of the present invention, there is provided a process for the treatment of a drill bit comprising the steps of subjecting said drill bit to deep cryogenic treatment, and coating said drill bit with a dry film fluorocarbon lubricant. A preferred lubricant is a resin-bonded fluoropolymer coating.
More particularly, the deep cryogenic treatment comprises the steps of tempering a drill bit at about 375xc2x0 F. for about two hours; cooling the drill bit slowly to ambient temperature; cooling the drill bit to approximately xe2x88x92120xc2x0 F., and soaking the drill bit at about xe2x88x92120xc2x0 F. until uniformly chilled; cooling the drill bit to about xe2x88x92300xc2x0 F. to about xe2x88x92340xc2x0 F. and maintaining the drill bit at about xe2x88x92300xc2x0 F. for two hours per inch of thickness; warming the drill bit to about xe2x88x92175xc2x0 F. and soaking the drill bit at xe2x88x92175xc2x0 F. until uniform in temperature; warming the drill bit to ambient temperature and soaking the drill bit in still air until the drill bit is uniformly at ambient temperature; tempering the drill bit at about 375xc2x0 F. by soaking the drill bit at about 375xc2x0 F. for two hours; and cooling the drill bit to ambient temperature.
In another aspect of the present invention, coating the drill bit with a dry film fluorocarbon lubricant comprises the steps of cleaning the drill bit; immersing the drill bit in a bath of the dry film lubricant; removing the drill bit from the bath; allowing the drill bit to dry at ambient temperature; and baking the drill bit for at least one baking time period at a baking temperature sufficient to bake the dry film fluorocarbon lubricant onto the drill bit.
In yet another aspect of the present invention, the dry film fluorocarbon lubricant is a resin-bonded fluoropolymer coating.
More particularly, the dry film fluorocarbon lubricant is Emralon 305(trademark) having a composition as follows, by volume:
The foregoing composition is relative to the final product, and 5 percent is lost through evaporation.
It has been found important to remove cuttings by means of a vacuum device. Such vacuum device can also serve to cool the drill bit.
In a still further aspect of the invention there is provided a novel drill bit particularly adapted for drilling paper produced by the process of the invention.